Conventional packer head machines for making a concrete pipe utilize a rotating packer head and a cylindrical outer jacket to form the concrete pipe. A pallet is located on a turntable adjacent the lower end of the jacket. A top table adjacent the upper end of the jacket has a hole for allowing the packer head to be located in the bottom end of the jacket. Concrete from a hopper and conveyor system is discharged through the hole into the jacket above the packer head. The pipe is formed by simultaneous rotation and elevation of the packer head. Gourlie et al. shows in U.S. Pat. No. 3,262,175 a packer head concrete pipe making machine.
The top table can be equipped with a feeding device. The feeding device has a plurality of blades that are rotatable to move the concrete from the top table into the jacket. An example of a feeding device is shown by Fosse et al. in U.S. Pat. No. 3,551,968. Another feeding device is shown by Miller in U.S. Pat. No. 1,137,776.
It has been found that to make a satisfactory bell end on a concrete pipe, a bell packer should be used. A bell packer is a mechanism that rotates and vibrates the pallet during the initial stages of making the pipe. A bell packer structure is shown by Tiller in U.S. Pat. No. 3,083,433.
Conduit forming machines having a plurality of packer heads are used to form a plurality of openings in a single pipe. The pipe is formed in a single outer jacket. The plurality of packer heads and cylindrical followers are used to make a plurality of passages through the pipe. Norton et al. in U.S. Pat. No. 3,095,628 shows this type of machine.
A machine for making a plurality of concrete pipes is disclosed by Steiro in U.S. Pat. No. 2,926,411. This machine has four jackets that are positioned about four upright cores. The concrete is placed in the annular spaces between the cores and the jackets to form the pipes. The machine does not use packer heads for making the pipes.